You would need to go to a doctor to find out whether it was an STD. Oral sex can transmit STDs, but it's usually the person giving the oral sex who's at risk, except for herpes, and your symptoms don't match herpes (some people have oral herpes, which comes out as cold sores, and if they're having an outbreak and go down on you, it can spread, but you're not getting blisters or anything that would suggest herpes). If someone has something like gonorrhea or chlamydia and you go down on them, you can get an infection in your throat. That could go the other way, but I think you'd notice an infection like that.
Some discharge is normal, and clear, white, and yellowish are all normal colors. It shouldn't be super clumpy or really foul-smelling though. Your vagina should have a smell though, and you should become familiar with the normal smell so that you can tell in the future if it changes. Bacterial vaginosis and yeast infections can arise spontaneously, without sexual activity being involved. Did you check for a tampon? I know it's gross, but if that's your problem it should be an easy fix. You can put gloves on if you're really grossed out by the idea.
You should see a doctor before resuming sexual activity, just to be safe. And make sure you use protection to prevent pregnancy and disease.
I have had discharge, and frequently a lot of it. I'm a Virgin but you don't think it could be an STD for like oral or something? Because I would cry if it was.
You should go see a gynecologist, who will be able to take a swab and look under a microscope, or do other tests. My first thought is bacterial vaginosis, since that can cause a bad smell, but it's really hard to say over the internet. Yeast infections itch, and usually come with "cottage cheese" discharge. Make sure you don't have a tampon stuck up there that you forgot to remove, because that can cause a really foul smell.